Apparatus and method for mounting components on substrate

ABSTRACT

An apparatus has a holder that receives a component from a component supply and then places the component on a substrate. In operation, it is determined whether the holder makes an interference with another component mounted on the substrate. If the judgement is affirmative, an mounting of the component held by the holder is prohibited. If, on the other hand, the judgement is negative, the component held by the holder is mounted on the substrate.

FIELD OF THE INVENTION

[0001] The present invention relates to an apparatus and method formounting electric components on a substrate such as circuit board.

BACKGROUND OF THE INVENTION

[0002] Referring to FIG. 31, there is illustrated a conventionalmounting apparatus generally indicated by reference numeral 1. Ingeneral, the system 1 includes a supply section 2 for supplying electriccomponents to the system 1, a placement head 3 for receiving thecomponent from the supply section 2 and then mounting the component on asubstrate such as circuit board, a transport unit 4 for transporting theplacement head 3, a recognition device 5 for taking a digital image ofthe component held by the placement head 3, a holding section 6 forreceiving and holding the substrate onto which the components aremounted, and a controller 7 for controlling an entire operation of thesystem 1.

[0003] In operation of the system 1, the placement head 3 moves to apredetermined position above the supply section 2 bearing a componentsupply cassette 11, for example, with a number of components 12. Avertically extending vacuum nozzle 13 in the form of quill supported bythe placement head 3 is moved down to receive the component 12. Theplacement head 3 is then rotated about a vertical axis, i.e. Z-axis, byan angle controller 14 so that the component is oriented in apredetermined direction. The recognition device 5 takes an image of thecomponent 12 supported by the nozzle 13 of the placement head 13 movingpast a predetermined position opposing the image processor 5. The imageis transmitted to an image processor 20 where the image is processedaccording to a specific image processing technique to determine aposition of the component, i.e., its horizontal and/or angulardisplacement relative to the nozzle. Information indicating the positionof the component is transmitted to the controller 7. Based upon theinformation, the controller 7 corrects the position of the component.Then, the nozzle 13 is moved above a predetermined placement position ofthe substrate 18 and then down toward the substrate 18 so that thecomponent 12 is mounted on the substrate.

[0004]FIG. 32 is a flowchart showing a conventional method for mountingcomponents. In this method, at step S1101, the nozzle 13 receives thecomponent 12. Then, at step S1102, the recognition device 5 takes apicture of the component 12 held by the nozzle 13. The picture isprocessed at the image processor 20. The position of the component 12 isdetermined at step S1103 whether the component 12 can be mounted on thesubstrate. If the component 12 is incapable of being mounted on thesubstrate, the nozzle 13 brings the component to a collect station (notshown) at step S1106. Otherwise, the horizontal and/or angulardisplacement of the nozzle 13 is determined at step S1104. Using thedisplacement, the horizontal position of the placement head 3 and/or theangular orientation of the nozzle 13 is adjusted. Finally, the component12 is mounted in position onto the substrate 18 at step S1105. In thisprocess, no judgement is made whether the nozzle 13 interferes with oneor more components mounted on the substrate 18.

[0005] In the meantime, the electric devices are likely to be smallsized and light-weighted, increasing a density of components mounted onthe substrate 18 considerably. For example, a clearance betweenneighboring components of about 1.0 mm×0.5 mm is decreased to about 0.2mm. Notwithstanding this, each component should be mounted on thesubstrate as it does not interfere with another component mounted on thesubstrate. To this end, used is the nozzle with a tip end designed to belarger than the small component 12.

[0006] However, where the clearance of the components is down to about0.1 mm, for example, a displacement of the component 12 relative to thenozzle 13 may result in an interference between the nozzle 13 and thecomponent 12 mounted on the substrate 18. This is illustrated in FIGS.33A to 34B. In each drawing, illustrated are nozzle 13 and components12, both viewed from the substrate. Specifically, in FIG. 33A, thenozzle 13 is shown so that it is angularly inclined to the component 12.In this instance, using the image of the component captured by therecognition device 5 and the result obtained by the image processor 20,the controller 7 corrects the horizontal and/or angular position of thecomponent 12 relative to the nozzle 13 before the mounting of thecomponent 12 so that the component is placed on a predetermined, correctposition on the substrate. However, as shown by hatched lines in FIG.33B, a part of the nozzle can result in an interference with anothercomponent 12 a mounted on the substrate. On the other hand, FIG. 34Ashows the nozzle and the component retained by the nozzle in which thecomponent is horizontally offset from a center of the nozzle. In thisinstance, as shown in FIG. 34B, the nozzle 13 is displaced so that thecomponent is mounted on a correct position on the substrate and this inturn results in an interference with another component 12 a mounted onthe substrate as shown by hatching.

[0007] Although not clearly shown in the plan views, i.e., FIGS. 33B and34B, since the component has a certain height, the interference may bemore problematic for the case with a reduced clearance when consideringa deviation of height and/or inclination of the component. That is, theinterference between the nozzle 13 and the component 12 a results inanother displacement of the component 12 a. What is worse, the component12 may be damaged, which results in a deterioration and/or malfunctionof the circuit.

SUMMARY OF THE INVENTION

[0008] Therefore, a purpose of the present invention is to provide anapparatus and method for mounting component on a substrate, which iscapable of mounting component on the substrate without any interferencebetween the nozzle and the component mounted on the substrate even whenonly a small clearance is ensured between the components on thesubstrate due to a requirement of compactness of the component.

[0009] To this end, according to the apparatus and method of the presentinvention, a holder receives a component from a component supply andthen places the component on a substrate. In operation, a judgement ismade whether the holder makes an interference with another componentmounted on the substrate. Then, if the judgement is affirmative, anmounting of the component held by the holder is prohibited. If, on theother hand, the judgement is negative, the component held by the holderis mounted on the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010]FIG. 1 is a flowchart showing a method for mounting components ona substrate according to a first embodiment of the present invention;

[0011]FIG. 2 is a flowchart showing a method for mounting components ona substrate according to another embodiment of the present invention;

[0012]FIG. 3 is an enlarged side. elevational view showing heights ofthe components mounted on the substrate;

[0013]FIGS. 4A and 4B are diagrams for describing a determination of aninterference between a component holder and the component mounted on thesubstrate;

[0014]FIG. 5 is a flowchart showing a method for mounting components ona substrate according to another embodiment of the present invention;

[0015]FIGS. 6A and 6B are diagrams for describing a determination of theinterference according to the method in FIG. 5;

[0016]FIG. 7 is a flowchart showing a method for mounting components ona substrate according to another embodiment of the present invention;

[0017]FIGS. 8A to 8C are diagrams for describing a determination of theinterference according to the method in FIG. 7;

[0018]FIGS. 9A to 9C are another diagrams for describing a determinationof the interference;

[0019]FIG. 10 is a schematic perspective view of the component mountingapparatus of the present invention;

[0020]FIG. 11 is a flowchart showing a method for mounting components ona substrate according to another embodiment of the present invention;

[0021]FIGS. 12A and 12B are diagrams for describing a determination ofthe interference according to the method in FIG. 11;

[0022]FIG. 13 is a flowchart showing a method for mounting components ona substrate according to another embodiment of the present invention;

[0023]FIG. 14 is a flowchart showing a method for mounting components ona substrate according to another embodiment of the present invention;

[0024]FIG. 15 is a schematic perspective view of another componentmounting apparatus of the present invention;

[0025]FIG. 16 is a side elevational view showing a part of the componentmounting apparatus with a rotary head;

[0026]FIG. 17 is a plan view showing an arrangement of placement headssupported by the rotary head;

[0027]FIG. 18 is a block diagram showing portions of a controller of thecomponent mounting apparatus;

[0028]FIG. 19 is a table showing an example of an NC program;

[0029]FIG. 20 is a table showing an example of an arrangement program;

[0030]FIG. 21 is a table showing an example of a parts library;

[0031]FIG. 22 is a flowchart showing a process for calculating aneighboring distance carried out at distance calculator in FIG. 18;

[0032]FIG. 23 is a diagram showing an area occupied by the component onthe substrate;

[0033]FIG. 24 is a diagram showing a distance between the neighboringareas;

[0034]FIG. 25 is a flowchart for determining the interference betweenthe holder and the component;

[0035]FIG. 26 is a flowchart showing processes carried out at thecomponent data section;

[0036]FIG. 27 is a perspective view of another component mountingapparatus;

[0037]FIG. 28 is a block diagram showing portions of the componentmounting apparatus;

[0038]FIG. 29 is an enlarged perspective view of the placement heads ofthe component mounting apparatus;

[0039]FIG. 30 is a schematic plan view of the component mountingapparatus in FIG. 29;

[0040]FIG. 31 is a schematic perspective view of the conventionalcomponent mounting apparatus;

[0041]FIG. 32 is a flowchart showing a conventional component mountingprocess; and

[0042]FIGS. 33A and 33B are schematic plan views for describing theinterference between the holder and the component.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0043] First Embodiment

[0044] With reference to the drawings, descriptions will be made to asystem and method for mounting a component onto a substrate or circuitboard according to the first embodiment of the present invention. Thesystem of the present invention has an appearance that is substantiallyidentical to the conventional system illustrated in FIG. 31. Namely, thesystem 1 has a component supply 2, a placement head 3 for receiving andmounting, a robot or transport device 4 for transporting the placementhead 3, a recognition device 5 for taking a picture of the componentheld by the placement head, a holder 6 for receiving and then holdingthe substrate, and a controller 7 for controlling an entire operation ofthe system.

[0045] Generally, the placement head 3 causes its nozzle 13 to receivethe component 12 from the component supply 2 and, while moving towardthe recognition device 5, rotate the nozzle about its vertical axis sothat the component orients in a predetermined mounting direction. Therecognition device 5 takes a picture of the component held by nozzle 13of the placement head 3. The picture is then processed by the imageprocessor 20 to determine the position of the component 12 on the nozzle13. The determined position is transmitted to the controller 7. Basedupon an instruction from the controller 7, the placement head 3corrects, if any, horizontal and/or angular displacement of thecomponent and then places the component in a predetermined area on thesubstrate 18. Typically, the picture of the component is taken while theplacement head 3 is moving toward the placement station. However,according to the type of the recognition device 5, the placement head 3may halt while taking the picture of the component.

[0046]FIG. 1 is a flowchart showing a process for mounting a componentaccording to an embodiment of the present invention, which is carried bythe controller 7. According to this program, at step S1 the component 12is received by nozzle 13 of the placement head. At step S2 therecognition device S picks up an image of the component held by nozzle.The image is transmitted to and then processed by the image processor20. Using a result obtained by the image processor 20, it is determinedat step S3 whether the component can be mounted on the substrate. If itis determined that the component is incapable of being mounted correctlyon the substrate, the program proceeds to step S7, causing the nozzle 13to discard the component at a collect station not shown. This occurswhere the component is considerably inclined to a surface of thesubstrate; the nozzle bears an incorrect component; or the component isoutside the field of the recognition device so that the recognitiondevice is unable to pick up the whole image of the component.

[0047] If it is determined at step S3 that component is in the conditionthat it can be mounted on the substrate, the program proceeds to stepS4. At this step, another determination is made whether, during themounting of the component, the nozzle 13 makes an interference with thecomponent mounted on substrate due to the horizontal and/or angularadjustment of the component relative to the nozzle. This determinationwill be described fully together with the specific embodiments. If, onthe other hand, it is determined at step S4 that there exists apossibility of the interference between the nozzle 13 and the component12 a mounted on the substrate, the program proceeds to step S7. At thisstep, the component 12 held by the nozzle 13 is discarded at the collectstation not shown. Indeed, there exists another option in which thenozzle 13 is moved and/or rotated to a certain extent in order to avoidthe interference at the mounting of the component 12, which will bedescribed in detail below. Then, the program proceeds to step S5 where ahorizontal and/or angular correction of the nozzle 13 required for themounting of the component 12 is determined. Subsequently, the nozzle 13is corrected and then the component 12 is mounted on the substrate 18 atstep S6. After the completion of the mounting or the discard of thecomponent, the nozzle 13 moves again toward the component supply 2 forthe next pickup operation of the component. The above steps are repeatedfor the subsequent components to be mounted on the substrate.

[0048] Second Embodiment

[0049] Next, referring to the drawings, descriptions will be made to thecomponent mounting apparatus and method according to the secondembodiment of the present invention. Basically, the structure ofappearance and operation of the system of this embodiment is similar tothat of the first embodiment described above, except for a process forthe prevention of the interference between the nozzle and the component.

[0050] Referring to FIG. 2, there is a process performed by thecontroller 7. In this process, the component 12 is supported on thenozzle at step S11. Then, a position of the component 12 held by thenozzle is determined at step S12, which is used for anotherdetermination at step S13 whether the component can be mounted on thesubstrate. If it is determined at step S13 that the component is unableto be mounted on the substrate in a proper way, the program proceeds tostep S19 where the component is discarded at the collect station. Theoperations described above are the same as those described for the firstembodiment.

[0051] If, on the other hand, it is determined at step 13 that thecomponent is held so that it can be mounted on the substrate, anotherdetermination is made at step S14. At this step, it is determinedwhether the nozzle 13 makes an interference with the component 12 amounted on the substrate at the placement of the component 12 held bythe nozzle 13. For this purpose, a first decision is made whether aheight of the component 12 held by the nozzle 13 is greater than that ofthe component 12 a around which the component 12 will be mounted. FIG. 3illustrates a spatial relationship between the component 12 held by thenozzle and the component 12 a mounted on the substrate. As shown in thedrawing, if the height of the component 12 to be mounted is equal to ormore than that of the mounted component 12 a, no physical interferencebetween the nozzle 13 and the mounted component 12 a will occur evenwhen the nozzle 13 overlaps the mounted component 12 a in a regionindicated by α. The heights of the components 12 and 12 a aretransmitted to and then stored in the controller 7 (see FIG. 31).Therefore, in this instance the program proceeds to step S17 where ahorizontal and/or angular correction of the nozzle is determined inorder to mount the component 12 in a predetermined position on thesubstrate. Based upon this determination, the component 12 is placed onthe substrate 18 at step S18.

[0052] If, on the other hand, the height of the component 12 is lessthan that of the mounted component 12 a, a calculation is made todetermine a relationship between the nozzle 13 and the mounted component12 a, i.e., whether the nozzle 13 makes an interference with the mountedcomponent 12 a.

[0053]FIGS. 4A and 4B schematically illustrate a spatial relationshipbetween the nozzle 13 and the component 12 held by the nozzle in whichit is assumed that the component 12 is improperly inclined to thenozzle. In this instance, according to the conventional technique, asbest shown in FIGS. 4A and 4B, the nozzle 13 is turned around to directthe component in a proper direction, which in turn can result in aninterference between the nozzle 13 and the mounted component 12 a.

[0054] However, according to the present invention, a new concept orreference area (safety region) 21 is used for determining whether thenozzle interferes with the mounted component. The reference area 21 ispredetermined in light of the position of the neighboring, mountedcomponent 12 a. In this embodiment, an outer periphery of the mountedcomponent 12 a defines a part of an outline of the reference area 21.Alternatively, as shown by a long and short dotted line in FIG. 4B, thereference area may be spaced away from the outer periphery of themounted component, leaving a certain clearance therebetween for safe.

[0055] An amount of horizontal and/or angular correction of thecomponent relative to the nozzle in FIG. 4A is calculated in light of aknown configuration and reference position of the nozzle. Also, theactual displacement of the component is determined by comparing theimage of the component taken by the recognition device and the knownconfiguration and reference position of the nozzle. The referenceposition of the nozzle 13, which is supposed with its center located atthe center 25 of the nozzle 13 as shown in FIG. 4A, is stored in thecontroller 7 or the imaging device 20. Also, in order to suppose thereference area 21, also used are a shape, size and position of thecomponent 12 a mounted on the substrate, stored in the controller 7.

[0056] Referring back to FIG. 2, using the calculation result made atstep S15, a determination is made at step S16 whether the nozzle 13stays within the reference area 21. When even a small part of the nozzle13 positions outside the reference area, it is determined that thenozzle 13 interferes with the mounted component 12 a. Then, at step S19the component 12 is discarded from the nozzle 13 without being mountedon the substrate. If, on the other hand, the nozzle 13 stays fullywithin the reference area 21, it is determined that no interferenceoccurs between the nozzle and the mounted component 12 a. Then, theprogram proceeds to step S17 where the horizontal and/angulardisplacement or the amount of correction of the component 12 iscalculated. Based upon this calculation, the displacement of thecomponent 12 is removed by moving the nozzle 13. Then, the component 12is placed on the substrate at step S18. After the completion of theplacement or discard of the component at step S18 or S19, the nozzlemoves back to the supply section 2 for the next pickup operation of thecomponent. Afterwards, the program returns to step S11 so that theabove-described procedures are performed again.

[0057] A clearance between the reference area 21 and the outline of themounted component may vary from one direction to the other directiondepending upon the features of the neighboring components. Also, thereference area 21 may be extended in one direction in the form of stripif no neighboring component exists in that direction and, therefore,there is no necessity for considering the possible interference in thatdirection.

[0058] If the component held by the nozzle has a greater height than theneighboring, mounted component, it can determine that there is nointerference between the nozzle and the mounted component. Therefore, inthis instance, the controller performs only steps S13 to S15 for everycomponent without making any determination at step S14. This alsoapplies to the following embodiments.

[0059] Third Embodiment

[0060] Referring to the drawings, descriptions will be made to anothersystem and method according to the third embodiment of the presentinvention. The basic structure of appearance and operation of the systemof this embodiment is similar to that of the first embodiment describedabove, except for a process for the prevention of the interferencebetween the nozzle and the component.

[0061] Referring to FIG. 5, there is shown a process performed by thecontroller 7. In this process, at step S21, the component 12 is receivedon the nozzle. Then, a position of the component 12 held by the nozzleis recognized at step S22, which is used for another determination atstep S23 whether the component can be mounted on the substrate. If it isdetermined at step S23 that the component is unable to be mounted on thesubstrate in a proper way, the program proceeds to step S29 where thecomponent is discarded at the collect station. The operations describedabove are the same as those described for the first embodiment.

[0062] If, on the other hand, it is determined at step 23 that thecomponent is held so that it can be mounted on the substrate, anotherdetermination is made at step S24. At this step, it is determinedwhether a height of the component 12 held by the nozzle 13 is greaterthan that of the component 12 a around which the component 12 will bemounted. If the height of the component 12 to be mounted is equal to ormore than that of the mounted component 12 a, the program proceeds tostep S27 where a horizontal and/or angular correction of the nozzle iscalculated. Based upon this calculation, the component 12 is placed onthe substrate 18 at step S28.

[0063] If, on the other hand, the height of the component 12 is lessthan that of the mounted component 12 a, the program proceeds to stepS25 where a position of the nozzle 13 above the substrate 18 at themounting of the component 12 is calculated. For example, if thecomponent 12 is inclined to the substrate 18 as shown in FIG. 6A,calculated are possible positions of the nozzle 13 on the substrate 18in which the component 12 is oriented in the proper direction as shownin FIG. 6B.

[0064] Based upon this calculation, another determination is made atstep S26 whether the nozzle 13 overlaps at least in part the component12 a which is supposed to have been mounted in a predetermined positionon the substrate 18. If the overlap is established, it is determinedthat the nozzle 13 interferes with the mounted component 12 a. In thisinstance, the component 12 is transported to the discard station at stepS29 without being mounted on the substrate. Otherwise, the programproceeds to step S27 where an amount of horizontal and/or angularcorrection of the placement head 3 is calculated. Based upon thiscalculation, a necessary horizontal and/or angular correction is made tothe placement head 3. Then, the component 12 is mounted on the substrate18. After the mount or discard of the component 12, the nozzle 13 isreturned to the supply section 2 for the pickup operation of thesubsequent component and, then, the program proceeds again to step S21.

[0065] As described above, although in the second embodiment thereference area is considered for the determination of the interference,in this embodiment the interference is determined using the position inwhich the neighboring component 12 a is supposed to have been mounted onthe substrate. For this purpose, information of not only the shape andsize of the nozzle 13 but also the shape and size and the mountedposition of the component 12 a are stored in the controller 7. Usingthis information, the controller 7 calculates the positions occupied bythe nozzle 13 and the component 12 a.

[0066] Fourth Embodiment

[0067] Next, referring to the drawings, descriptions will be made toanother component mounting apparatus and method according to the fourthembodiment of the present invention. The basic structure of appearanceand operation of the system of this embodiment is similar to that of thefirst embodiment described above, except for a process for theprevention of the interference between the nozzle and the component.

[0068] Referring to FIG. 7, there is shown a process performed by thecontroller 7. In this process, at step S31, the component 12 is receivedon the nozzle. Then, a position of the component 12 held by the nozzleis recognized at step S32, which is used for another determination atstep S33 whether the component can be mounted on the substrate. If it isdetermined at step S33 that the component is unable to be mounted on thesubstrate in a proper way, the program proceeds to step S39 where thecomponent is discarded at the collect station. The operations describedabove are the same as those described for the first embodiment.

[0069] If, on the other hand, it is determined at step 33 that thecomponent is held so that it can be mounted on the substrate, anotherdetermination is made at step S34. At this step, it is determinedwhether a height of the component 12 held by the nozzle 13 is greaterthan that of the component 12 a around which the component 12 will bemounted. If the height of the component 12 to be mounted is equal to ormore than that of the mounted component 12 a, the program proceeds tostep S37 where an amount of horizontal and/or angular correction of theplacement head 3 is calculated. Based upon this calculation, thecomponent 12 is placed on the substrate 18 at step S38.

[0070] If, on the other hand, the height of the component 12 is lessthan that of the mounted component 12 a, the program proceeds to stepS35 where, as shown in FIG. 8B, irrespective of the size of the mountedcomponent 12 a, an reference area 21 a is determined from the size ofthe component 12 in an image processing so that it is greater than thesize of the component 12 by a certain length. A size of the expandedarea of the reference area can be determined arbitrarily. The size ofthe reference area may be determined using a predetermined limitdistance from the neighboring component, stored in the controller asshown in FIG. 21.

[0071] Referring back to FIG. 7, it is determined at step 36 whether thenozzle 13 stays within the reference area 21 a in light of size andshape of the nozzle 13, the reference position of the nozzle 13 (e.g.,its center 25), and the position of the component 12 relative to thenozzle 13 determined at step S32. If not, the program proceeds to stepS39 where the component 12 is discarded at the collect station.Otherwise, the program proceeds to step S37 where an amount ofhorizontal and/or angular correction of the placement head 3 iscalculated. Based upon this calculation, a horizontal and/or angularcorrection is made to the placement head 3. Then, the component 12 ismounted on the substrate 18 at step S38. After the mount or discard ofthe component 12, the nozzle 13 is returned to the supply section 2 forthe pickup operation of the subsequent component and, then, the programproceeds again to step S31.

[0072] The size of the reference area 21 a may be varied from onedirection to the other direction according to the arrangement of thecomponents on the substrate, in particular, neighboring component orcomponents. Also, the reference area 21 a may be extended in a certaindirection in the form of strip if no neighboring component exists inthat direction and, therefore, there is no necessity for considering thepossible interference in that direction. Further, if there is a possibleinterference only in one direction, as shown in FIG. 8C the referencearea may be defined only in that direction.

[0073] In the embodiments described above, the amount of horizontaland/or angular displacement of the component 12 relative to the nozzle13 is determined by comparing the known shape and size and the presetreference holding position of the nozzle 13 (e.g., the center of thenozzle 13) with the image picked up by the recognition device 5.However, instead of using such known shape and size and the presetreference holding position of the nozzle 13, they may be determined fromthe image picked up by the recognition device 5 and then used for theposition determination. This also ensures a precise determinationwhether there is a possible interference between the nozzle 13 and themounted component 12 a.

[0074] Also, in the previous embodiments whether the nozzle 13interferes with the mounted component 12 a is determined by the imageprocessor 20, it may be performed by the controller 7.

[0075] Further, although in the previous embodiments the placement head4 is transported in a horizontal plane by the robot 4, a rotary mountingdevice having a plurality of placement heads arranged on a circle androtating successively for mounting may be used instead.

[0076] Fifth Embodiment

[0077] Referring to the drawings, descriptions will be made to thesystem and method according to the fifth embodiment of the presentinvention. In this embodiment, the system has another imaging device forpicking up an image of the substrate 18 in order to establish theposition of the component 12 a mounted on the substrate and thereby todetermine a possible interference between the nozzle 13 and the mountedcomponent 12 a. For example, as shown in FIG. 9A, in the previousembodiment it is determined whether the nozzle 13 of which horizontaland/or angular position has been adjusted falls at least in part in thereference area 22 defined by the position of the mounted component 12 a.However, a certain condition may be thought that as shown in FIG. 9B thecomponent 12 a is mounted on the substrate in an inclined fashion withrespect to a predetermined direction and position. In this instance,even though the nozzle 13 stays within the reference area 22, therestill exists some possibility to cause the interference between thenozzle 13 and the mounted component 12 a. However, when the component 12a is inclined in the opposite direction as shown in FIG. 9C, nointerference would occur even if a part of the nozzle 13 is locatedoutside the reference area 22.

[0078] Therefore, according to this embodiment, the position of themounted component 12 a is obtained and then used in the determinationwhether the nozzle 13 interferes with the mounted component 12 a. Forthis purpose, as shown in FIG. 10, a component mounting apparatus 30 hasa second image processor 31 for recognition of the component 12 amounted on the substrate 18. Preferably, the image processor 31 ispositioned on the placement head 3 near the nozzle 13. Other structuresof the system 30 are similar to or identical to those described in theprevious embodiment, so that no description is made thereto.

[0079] Referring to FIG. 11, there is shown a flowchart indicating acomponent mounting process performed by the controller 7. The flowchartis similar to that described with respect to the second embodiment,except that the image processor 31 recognizes the position of thecomponent 12 a mounted on the substrate 18 at step S41. The recognitionis carried out after the placement head 3 has reached a position whereit places the component 12 on the substrate 18, preferably after thecompletion of the placement of the component 12. The image of themounted component 12 a is transmitted to the image processor 20 or thecontroller 7 where it is used at step S47 to define the reference area.

[0080] For example, as shown in FIG. 9D, a deformed reference area 22 amay be defined for the inclined component 12 a. The deformed referencearea 22 a ensures to prevent the interference between the nozzle 13 andthe component 12 a placed improperly. Also ensured is a proper mountingof the component 12 which would be prohibited from being mounted whensupposing a non-deformed reference area as shown in FIGS. 9A to 9C. Theimage processor 31 may be provided on another moving member rather thanthe placement head 3. In this instance, the image processor 31 with themoving member may oppose the substrate 18 for the recognition of thesubstrate 18 while the placement head 3 is away from substrate 18.

[0081] Sixth Embodiment

[0082] Referring to the drawings, descriptions will be made to anothersystem and method according to the sixth embodiment of the presentinvention. In this embodiment, the component 12 which is discarded dueto the possible interference between the nozzle and the mountedcomponent is allowed to be mounted on the substrate 18 by adjusting thehorizontal and/or angular position of the nozzle while preventing theinterference of the nozzle and the mounted component. That is, in thesecond embodiment, as shown in FIG. 4B if the nozzle 13 protrudes beyondthe reference area 21, the component 12 is discarded without beingmounted on the substrate 18. However, as shown in FIGS. 11A and 11B,even in the same condition the nozzle 13 rotates in a directionindicated by arrow 27 so that it stays wholly within the reference area21, allowing the component 12 to be mounted on the substrate 18. Thisnot only prevents the interference between the nozzle and the componenton the substrate but also increases an efficiency of the mounting.

[0083] Although in the previous embodiment the nozzle 13 is rotated intothe reference area, it may be transported linearly in a direction awayfrom the component 12 a on the substrate 18. Also, the rotationalmovement may be combined with the liner movement.

[0084] The above adjustment of the nozzle 13 can cause the component 12to incline as indicated by the solid line, relative to the properposition on the substrate indicated by the long and short dotted line 12b. This may increase a likelihood of the interference between thecomponent 12 mounted on the substrate and the nozzle 13 in the placementmovement for the subsequent component. However, the interference isprevented by reducing a size of the reference area 21 according to theinclination in the formation of the region for the subsequent component.The nozzle 13 is discarded unless the nozzle 13 enters entirely withinthe reference area.

[0085]FIG. 13 is a flowchart showing the component mounting method ofthis embodiment. In this flowchart, processes performed at steps S11 toS19 are the same as that described with regard to the second embodimentof the present invention. If it is determined at step S16 that thenozzle 16 is outside the reference area, another determination is madeat step S61 whether the nozzle would be entirely entered within thereference area by the liner and/or rotational movement of the nozzle. Ifthe result is affirmative, the position of the nozzle is adjusted atstep S17 so that the nozzle entirely stays within the region. Then, thecomponent held by the nozzle is mounted on the substrate at step S18.Otherwise, the component 12 is discarded at the collect station.

[0086] Although this embodiment has been described in combination withthe second embodiment, it can equally be combined with anotherembodiments described above using the reference area. In particular, inthe combination of this embodiment with the fifth embodiment, since theinterference is determined after the recognition of the position of thecomponent 12 a on the substrate, the inclination of the component 12provides no adverse affect to the mounting of the subsequent component.

[0087] Seventh Embodiment

[0088] Referring to a flowchart in FIG. 14, descriptions will be made toanother system and method according to the seventh embodiment of thepresent invention. In this embodiment, data of interference between thenozzle 13 and the component 12 a on the substrate 18 is collected in theprocess of mountings for one or more certain number of substrates. Then,the collected data is used for the protection of the interference in thesubsequent mountings. For example, in mountings for the predeterminednumber of substrates, interference data including the number, thedegree, and position of interference caused between the nozzle and thecomponent is memorized. The data is processed statistically, forexample, to obtain a tendency of interference or inclination. Thistendency shows, for example, when and/or where the interference islikely to occur. Therefore, if that tendency is confirmed at step S72,an adjustment is made to cancel or reduce the tendency, preventing theinterference between the nozzle 13 and the component 12 a on thesubstrate 18.

[0089] The adjustment may be made by the rotation and/or horizontalmovement of component 12 to be mounted and/or 12 a mounted on thesubstrate. If, by the adjustment, the former tendency is eliminated butanother tendency is appeared in the predetermined number of subsequentmountings, a further adjustment is made to cancel or reduce the lattertendency. In this instance, the adjustment may be made to either of twocomponents 12 and 12 a alternatively or both. When adjusting bothcomponents, the amount of adjustment may be divided substantiallyequally for two components.

[0090] Eighth Embodiment

[0091] Referring to the drawings, descriptions will be made to anothersystem and method according to the eighth embodiment of the presentinvention. As described with reference to FIG. 3, when the height of themounting component 12 is greater than that of the mounted component 12a, no interference occurs between the nozzle 13 and the mountedcomponent 12 a. This in turn means that no interference is made bymounting components in an order in which the lower component is mountedearlier than the higher component. Therefore, according to thisembodiment, the components are mounted in the reverse order of height,preventing the interference of the nozzle and the mounted component orcomponents without any necessity of defining the reference area or ofrecognizing the size of the mounted component.

[0092] In this case, it is not necessary to determine the mounting orderfor all components to be mounted on the same substrate. This is becausethe nozzle 13 may interfere only with the component 12 a positioned inan area in which the component 12 will be mounted and may not interferewith the component 12 a positioned away from the area. Then, it isadvantageous to define several blocks on the substrate, each of whichblock including only components that would cause the interferencebetween the nozzle and the mounted component. In this instance, theorder of mounting of the components is determined for each block. Also,it is unnecessary to determine the interference between the nozzleholding the component to be mounted in one block and the mountedcomponent or components in another block away from one block. Eachheight of the components to be mounted on one substrate is availablefrom component data pre-stored in the controller 7.

[0093] Ninth Embodiment

[0094] Referring to the drawings, descriptions will be made to anothersystem and method according to the ninth embodiment of the presentinvention. In this embodiment, the interference determination using thereference area 21 is performed to the rotary type component mountingapparatus.

[0095] As shown in FIGS. 15 and 16, the component mounting apparatus 100generally includes a component supply section 110 for supplyingelectronic components successively, a rotary head 112 for receiving andthen mounting the components on a substrate 18, and an X-Y table 114 forpositioning the substrate 18. With this arrangement, the substrate 18 issupplied from a substrate supply section 116 and then positioned on theX-Y table 114. The rotary head 112, on the other hand, receives thecomponents 12 from the component supply section 110. A position of eachcomponent on the rotary head 112 is corrected, if necessary. Thecorrected component is then mounted on the substrate 18. After thecompletion of the mountings of the components, the substrate istransported from the X-Y table to a substrate discharge station 118.

[0096] In addition, the system 100 has an input section 120 for the datainput, a display station 122 for the data display, and a controller 107for controlling operations of the devices in the system. The input dataincludes sizes of the components and control data and the display dataincludes data showing the condition of the devices in the system.

[0097] Referring to FIG. 16, the component supply section 110 has a setof parallel parts cassettes 11 each holding a number of electroniccomponents 12. The set of parts cassettes is supported so that it canmove back and forth in a direction perpendicular to the drawing, whichensures each of the parts cassettes to provide its component for acomponent supply region 110 a. The X-Y table 114 is supported so that itmoves between the substrate supply section 116 and the substratedischarge section 118. At the substrate supply section 116, the table114 reaches a position communicated with a substrate inlet where itreceives the substrate on which the components will be mounted. Then,the table 114 holds and then transports the substrate 18 into aplacement position where the components are mounted thereon by therotary head 112. At the placement position, the table 114 moves left toright and back and forth so that each component is mounted on apredetermined, corresponding position on the substrate. After thecompletion of the mountings of the components, the table 114 moves to aposition adjacent to the substrate discharge section 118 for thedischarge of the substrate to the substrate discharge station 118.

[0098] For example, as shown in FIG. 17, the rotary head 112 has 12placement heads at regular intervals on its periphery. Each of theplacement heads 126 has five nozzles 132 for holding components ofdifferent sizes and is supported so that it moves up and down androtates about a central, vertical axis thereof. This allows that, whencatching and mounting the component, each nozzle 132 takes an outermostposition on a circle indicated by long and short dotted line in FIG. 17.

[0099] In operation, each placement head 126 is transported by the indexrotation of the rotary frame 128 from component supply position 110 a ofthe component supply section 110 to an opposite, component placementposition and then back again to the component supply position 110 athrough various stations.

[0100] Discussions will be made to operations carried out at eachstation. At station 1 (ST1), i.e., drawing station, the nozzle 132 facesthe component supply position and receives the component 12 fromcomponent supply section 110. Then, the thickness of the component heldby the nozzle 132 is measured at ST3 by a two-dimensional line sensornot shown, which is then transmitted to the system 100. The system 100determines whether the thickness measured is less than a predeterminedvalue. If the determination is affirmative, the system recognizes thatno component is supported by the nozzle or the component is incorrectlysupported by the nozzle. Otherwise, at ST 4 (i.e., pickup station), atwo-dimensional CCD camera (i.e., displacement detector) picks up a planimage of the component held by the nozzle 132 from its below. Using theimage, a horizontal and/or angular displacement of the component isdetermined, which is then transmitted to the system 100. At ST6, thenozzle rotates about its vertical axis according to the determined,horizontal and/or angular displacement to orient the component in aproper direction.

[0101] At ST7 (i.e., mount station), by the use of the result obtainedat the image processor, the X-Y table is positioned. Then, the placementhead 126 moves down to place the component onto the substrate 18 inposition. If it has been determined at ST 3 or ST4 that the component isincorrectly supported on the nozzle or the wrong component is supportedon the nozzle, the component is discarded from the nozzle at respectivestations. At ST11 (i.e., nozzle select station), the placement head 126is rotated about its vertical axis depending upon the component to bemounted to place the corresponding nozzle 132 into the outermostposition 134.

[0102] The angular displacement may be corrected by the rotation of theplacement head. This results in a further horizontal displacement of thecomponent, which is eliminated by the movement of the X-Y table.

[0103] Next, discussions will be made to an embodiment for mounting thecomponent by the system 100. This method is featured in that adetermination is made whether the nozzle or the component supported onthe nozzle makes an interference with the component mounted on thesubstrate, by the use of various criterions.

[0104] For this purpose, as shown in block diagram of FIG. 18, thesystem 100 includes various portions for its controlling. The controller107 has an NC data store section 141 for storing data defining amounting position of each component on the substrate; an arrangementdata store section 142 for storing data of the supply position of eachcomponent defined in the NC data and the types of components; acomponent data store section 143 for storing data defining features suchas the shape of each component and the type of each nozzle; a nozzlesize data store section 144 for storing data defining the size of eachnozzle; a calculator 145 for calculating each distance between twoneighboring components on the substrate in both, X and Y directionsusing data provided from the stores 141, 142, and 143; a distance datastore section 146 for storing the calculated distances by the calculator145; and an interference judge 148 for judging the existence of theinterference using data from the data store section 146 and alsodetermining a suitable clearance for each component and mountingposition.

[0105] In order to mount the components onto the substrate, the system100 includes NC program, arrangement program, and component library, forexample, stored therein. As shown in FIG. 19, the NC program defines anorder of components to be mounted and has supply positions (Z-number)and placement positions (X- and Y-coordinates) of the components. As canbe seen from the drawing, one line of such data is prepared for eachcomponent.

[0106] As shown in FIG. 20, the arrangement program 152 defines datathat includes the shape of component for each Z-number by the use ofassociated code in order to distinguish the type of component to besupplied.

[0107] As shown in FIG. 21, the component library 153 defines data ofcomponent shape code, component feature code, operational condition,supply condition, and neighboring condition. For example, the componentshape code defines the type of component. The component feature codedefines the size of the component. The supply condition defines how andby what the component is supplied. The neighboring condition defines thesize of the nozzle and the clearance between the neighboring componentson the substrate in order to determine the interference between thenozzle or component to be mounted and the component mounted.

[0108] The interference can be determined using a constant, limitdistance defined for the prevention of the interference. However, inthis procedure nothing is considered about the neighboring condition ofthe components. Therefore, according to the present invention, the limitdistance is automatically determined by taking the neighboring conditioninto account for each mounting of component, rather than using theconstant, limit distance.

[0109] The NC program 151, arrangement program 152, and componentlibrary 153 are established and stored prior to the actual mounting ofthe components. Then, a program for mounting is generated by thecombination of the NC program 151 corresponding to the substrate onwhich the components are mounted and the arrangement program 152defining the component supply positions and the shapes of the componentsdesignated in the NC library 153 with the component shape codes.

[0110]FIG. 22 shows a flowchart for calculating a distance between twoneighboring components mounted on the substrate and made at a distancecalculator 145. In this flowchart, at step S111 NC data store section141 provides a mounting, horizontal and angular position (x and ycoordinates and θ) of the component on the substrate. At step S112, thearrangement data store section 143 provides the shape code of thecomponent. Then, at step S113 the component data store section 143provides dimensions in the x and y directions of the componentcorresponding to the shape code. The distance calculator 145 calculatesan area (x_(s), y_(s)) on the substrate to be occupied by the componentat step S114. The area (x_(s), y_(s)) is stored a distance data storesection 146.

[0111] For example, the area (x_(s), y_(s)) is defined by the followingequations: $\begin{matrix}{{x_{p} - \frac{\left( {{L\quad \cos \quad R} + {W\quad \sin \quad R}} \right)}{2}} \leq x_{s} \leq {x_{p} + \left( \frac{{L\quad \cos \quad R} + {W\quad \sin \quad R}}{2} \right)}} & (1) \\{{y_{p} - \frac{\left( {{L\quad \sin \quad R} + {W\quad \cos \quad R}} \right)}{2}} \leq y_{s} \leq {y_{p} + \left( \frac{{L\quad \sin \quad R} + {W\quad \cos \quad R}}{2} \right)}} & (2)\end{matrix}$

[0112] wherein, as shown in FIG. 23,

[0113] x_(p), y_(p): coordinates of center of the component,

[0114] R: angle of the component, and

[0115] L, W: dimensions of the component.

[0116] This calculation is performed for every component to be mountedon the substrate at step S115. Then, the area of one component P isprovided from the distance data store section 146. Next, anothercomponent leaving a minimum distance from the component in eitherdirection is determined. This process is illustrated in FIG. 24 inwhich, for one component P, selected in x-direction is the component P1that leaves a minimum distance Δx from the component P and selected iny-direction is another component Pu that leaves a minimum distance Δyfrom the component P. For example, as shown in FIG. 24, the x-coordinate(x_(l)) of the center of the selected component P1 and the y-coordinate(y_(u))of the center of the selected component Pu are defined asfollows:

X _(lmin) ≦X _(ls) ≦X _(lmax)  (3)

Y _(u min) ≦Y _(us) ≦Y _(u max)  (4)

[0117] Then, the minimum distance in the x- and y-directions from thecomponents Pl and Pu, respectively, are determined as follows:Δ

Δ≅x _(p min) −x _(l max)  (5)

Δy≅y _(u min) −y _(p max)  (6)

[0118] wherein x_(lmin) and x_(lmax) are the minimum and maximumx-coordinates of the component Pl, respectively, Y_(umin) and Y_(umax)are the minimum and maximum y-coordinates of the component Pu,respectively, and x_(pmin) and Y_(pmax) are the minimum x-coordinate andthe maximum y-coordinate of the component P, respectively. Thecalculated distance Δx and ≢y are stored in the distance data storesection 46 at S117.

[0119] Referring to FIG. 25, there is shown a flowchart of the procedurefor the determination of the possible interference of the component,performed before the mounting of the components 12. In this program,according to the preset mount program, among a number of parts cassettesprepared at the component supply 110 one parts cassette 11 bearing adesired component 3 designated by the mount program is moved to thecomponent supply position 110 a. The component 12 is received by thenozzle 132 of the placement head 126 positioned at the component supplysection ST1 of the rotary head 110 a at step S121.

[0120] Then, the rotary head 112 is subject to the index rotation totransport the placement head 126 with the component into the recognitionstation ST4 where the component is recognized by the two-dimensional CCDcamera at step S122. The image recognized by the recognition device isused to determine the relative relationship between the nozzle 132 andthe component 12 in the x and y directions at step S123. That is, atthis step, it is determined the offsets of the nozzle 132 from thecomponent 12 in the x- and y-directions. Each offset bears a plus orminus sign. Then, the neighboring distance information for the componentsupported by the nozzle is retrieved from the distance data storesection 146 at step S124. Then, another determination is made at stepS125 whether the offset of the nozzle 132 from the component, calculatedat step S123, is less than the neighboring distance retrieved in eitherdirection. If the offset is greater than the neighboring distance, thereexists a possible interference between the nozzle or the componentsupported on the nozzle and another component mounted on the substrate.Therefore, at step S126 the placement head 126 is moved to the discardstation ST6 where the component is released from the nozzle into acollect container not shown. The same component is then picked up againby the nozzle and, if there is no possible interference, mounted on theposition of the substrate where the discarded component was intended tobe mounted. If, on the other hand, the offset is less than theneighboring distance, the component is mounted at step S127 on apredetermined position of the substrate. If it is determined that theabove steps are performed for every component, the program is completedat step S128.

[0121] According to the mounting method of this embodiment, data isautomatically generated for determining the interference between thenozzle or component supported on the nozzle and another componentmounted on the substrate for the nozzle and each component. Thiseliminates a complicated input process of the respective neighboringdistances at the generation of the mounting program. Also, conventionaldata can also be used in this method without any necessity ofmodification. This means that no complicated operation is needed for theinput of new data for the mounting. Also, the interference is checkedfor each component independently, which prevents the unwanted discard ofthe component capable of being mounted. This ensures an effectivemounting of the components. Further, immediately after the discard ofone component, the same component is mounted on the substrate withoutmoving the rotary head, which ensures to reduce a total time of themounting.

[0122] Tenth Embodiment

[0123] Discussions will be made to another system and process formounting of the component according to the tenth embodiment of thepresent invention. Generally, in this embodiment, data of the componentsmounted on the substrate are used for the determination of theinterference.

[0124] This method is preferably used in the system 100 shown in FIGS.15 to 17. In particular, in addition to the structures shown in FIG. 18,the system 100 further includes a memory section 147 for holding a listof positions of the components mounted on the substrate, which listbeing dynamically updated after the mounting of each component. A nozzleinterference check section 148 determines for each component supportedon the nozzle whether it will make an interference with any componentmounted on the substrate using data from the memory sections 144, 146and 147. In each determination, a suitable neighboring limit distance iscalculated for each component and its position.

[0125] Referring to FIG. 26, there is shown a flowchart indicatingprocedures carried out at the memory section 147 in FIG. 18 duringmounting. For example, when a new substrate is introduced into thesystem 100, the memory section 147 clears the list of positions of thecomponents mounted in the mountings for the previous substrate at stepS131. After a new component is supported on the nozzle at step S132, itis determined at step S133 whether another components neighboring thenew component on the substrate has been mounted on the substrate. If theneighboring component has already been mounted on the substrate, theinterference check is made only for that neighboring direction accordingto the procedures described in the ninth embodiment at steps that followstep S134. Otherwise, no interference check is made and the componentsupported by the nozzle is mounted on the substrate at step S139.

[0126] According to the mounting method of this embodiment, if the datashows a possibility of interference between the neighboring componentsbut no interference would occur when considering the actual mounting,the interference check is eliminated. This means that minimum checks arecarried out, shortening a time for mounting of each component.

[0127] In the previous embodiment, when it is determined that the nozzleor the component supported on the nozzle interferes with the mountedcomponent, the supported component is discarded without being mounted onthe substrate and then another component is held by the nozzle for itsmounting. In this instance, however, the system may simply bede-energized and then make a warning to an operator of this system. Thisallows the operator to determine whether the component supported on thenozzle should be discarded.

[0128] Although the ninth and tenth embodiments have been described incombination with the system 100 having the rotary head 12, they areequally applied to the system 1 in which the placement head moves backand forth on the substrate fixed in the system shown in FIG. 31 andanother system shown in FIGS. 27 and 30 in which the placement head hasa plurality of nozzles for supporting plural components simultaneously(see FIG. 29). The devices equipped in the system in FIG. 27 areoperationally connected to each other as shown in FIG. 28.

[0129] The system 200 has a guide portion including a pair of guiderails 252 each extending from a substrate supply section 216 through asubstrate support section 217 to a substrate discharge section 218 eachlocated at the center of a base frame 250. This allows that thesubstrate 18 introduced at the supply section 216 is transported to thesupport section 217 where the components are mounted thereon and thendischarge from the discharge section 218. A base frame 250 arrangedabove the substrate 18 is provided on its opposite sides with y-axisrobots 260 and 262 which in turn support an X-axis robot 264 so that bythe driving of the y-axis robots 260 and 262 the x-axis robot moves backand forth in the x-direction. This allows the placement head 266 to bemoved horizontally in the x-and y-directions. Each robot has a transportmechanism. For example, the transport mechanism has a nut secured to amovable member and a threaded shaft secured to a fixed member anddrivingly connected to a motor so that, by the driving of the motor, theshaft rotates to transport the movable member back and forthalternately.

[0130] The placement head 266 supported by the X-Y transport mechanismwith the x-axis robot 264 and y-axis robots 260 and 262 supports acomponent by its nozzle 232 for its placement onto a predeterminedposition of the substrate. The component may be a circuit chip such asresistor and condenser supplied from a parts cassette, for example, andanother large electronic device such as IC connector (e.g., SOP and QFP)supplied from a parts tray, for example. The mounting procedures arecontrolled by the controller 207 in FIG. 28 according to a programmemorized is and preset in the memory 1001. The program may be inputtedby manually using keys prepared at an operation panel, for example.

[0131] The parts cassettes 11 are arranged on opposite sides of thepaired guide rails 252, e.g., on the right upper and left lower sides.Each parts cassette 11 has a strip-like component holder wound about areel and holding a number of components or circuit chips such asresistors and condensers. The parts tray 26B, on the other hand, cansupport a pair of two trays 268 a extending perpendicular to the guiderails, respectively. Each tray 268 a slides toward the guide rails 252according to the number of components to be supplied so that thecomponent supply portion stays at a predetermined pickup position withrespect to the y-direction. Typically, the tray 268 a supports a numberof electronic components such as QFP.

[0132] A image processor 220 is provided near the substrate positionedby the pair of guide rails 252 in order to detect a two dimensionaldisplacement or the position of the component supported by the nozzle232 and also to cancel the displacement by the movement of the head 266.The image processor has a recognition device at its bottom and a housingsurrounding around the recognition device. A number of light emitterssuch as light emitting diodes are provided stepwise inside the housingfor the illumination of the component supported on the nozzle. Thisallows that light is emitted from various directions toward a mountingsurface of the component, which ensures to pick up a clear image of thecomponent with a suitable angle irrespective of the type of thecomponent. The angle is predetermined for each component according tothe preset component recognition data. The image picked up by the imageprocessor 220 is processed by the controller to determine the center ofthe component and positions of the electrodes to be used for thecorrection of the placement position and/or angle.

[0133] As shown in FIG. 29, the transport head 266 has a componentholder or a multiple head with a plurality of placement heads (e.g.,first to fourth placement heads 226 a to 226 d of the same structure).Each placement head has a nozzle 232, an actuator 278 for moving thenozzle 272 up and down, and a pulley 284. The pulleys 284 of the firstand third placement heads 226 a and 226 c are drivingly connectedthrough a timing belt 282 to a θ-rotation motor 280 a so that thenozzles 232 of the heads can rotate about respective vertical axesthereof simultaneously. The pulleys 284 of the second and fourthplacement heads 226 b and 226 d are connected through another timingbelt 282 to another θ-rotation motor 280 b so that the nozzles 232 ofthe heads can rotate about respective axes thereof simultaneously. Eachactuator 278 is made of air-cylinder, for example, so that by turning onand off the air-cylinder the nozzle head 232 moves up and down forreceiving and holding of the component. Although as shown in FIG. 29 therotation of the motor 280 a is transmitted through the timing belt torotate the nozzles 232 of the placement heads 226 a and 226 c and therotation of the motor 280 b is transmitted through another timing beltto rotate the nozzles 232 of the placement heads 226 b and 226 d, eachof the placement heads 226 a-226 d is connected to an individual motorfor its θ-rotation. However, in order to reduce the weight of the unitof the placement heads, the number of motors is minimized.

[0134] Each nozzle 232 of the placement head is replaceable and sparenozzles are accommodated in a nozzle stacker 286 mounted on thesubstrate 250 of the system 200. Generally, a various nozzles are usedsuch as small size nozzle for the chips of about 1.0 mm×0.5 mm andmedium size nozzle for QFP of about 18 mm×18 mm.

[0135] In operation, the substrate 18 is introduced at the supplysection 216 of the paired guide rails 252 and then transported into theholding section 217. Then, the placement head 266 is moved by the X-Yrobot transversely or horizontally in the X-Y plane to receive thepredetermined component from the parts cassette 11 or parts tray 268.The component is then passed by the recognition device of the imageprocessor 220 to recognize the position of the component supported bythe nozzle. Using the position of the component, the motor drives torotate the nozzle 232 for the correction of the position of thecomponent, if necessary. Then, the component is placed on thepredetermined component mounting position on the substrate 18.

[0136] Each of the placement heads 226 a-226 d moves down the nozzle 232vertically, i.e., in the z-direction, by the driving of the actuator 278when catching the component from the parts cassette 11 or the parts tray268 and also when placing the component onto the substrate 18. Also, thenozzle is replaced depending upon the type of the component.

[0137] By the repetition of the catching and mounting, all of thecomponents are mounted on the substrate. The substrate onto which everycomponent has been mounted is transported from the holding section 217to the discharge section 218. Then, a new substrate is introduced fromthe supply section 216 into the holding section 217 where the componentsare mounted on the substrate.

[0138] An inertial force generated at the acceleration and decelerationof the component and an adhering force between the component and thesubstrate should be considered when deciding a vacuum force applied fromthe nozzle to the component. Therefore, the components are divided intoseveral groups, i.e., high speed, medium speed, and low speed mountingcomponents depending upon the weight and size thereof.

[0139] Also, a plurality of placement heads may be used for thesimultaneous catching and/or mounting of the components.

[0140] In operation of the system 200, each distance of the neighboringcomponents is calculated according to the program shown in FIG. 22 andthen stored in the memory unit 146. As shown in FIG. 30, the substrate18 is transported from the supply section 216 into the holding section217. On the other hand, the component is picked up from the partscassette or pats tray 268 by the placement head 216 driven according tothe mounting program. Next, similar to the ninth and tenth embodiments,the interference is checked for the component supported on the nozzleaccording to the flowchart shown in FIG. 25. For this purpose, while theplacement head moves above the image processor 220, the recognitiondevice takes a picture of the component supported on the nozzle. Usingthe image picked up by the recognition device, the position or thedisplacement of the component relative to the nozzle is determined.Then, it is determined whether the displacement of the componentrelative to the nozzle is less than the neighboring distance derivedfrom the data unit 146. If the placement is greater than the neighboringdistance, the component is discarded. Otherwise, the component ismounted on the substrate. The interference check between the nozzle orcomponent supported on the nozzle and the component mounted on thesubstrate is performed as described in the second embodiment.

[0141] Eleventh Embodiment

[0142] Discussions will be made to the eleventh embodiment of thepresent invention. This embodiment is directed to a computer readablerecording medium. In this medium, a program having procedures forjudging the interference between the nozzle 13, 132, and 232 and themounted component 12 a is recorded therein. For example, the program hasseveral steps of

[0143] catching the component from the component supply by the componentholder;

[0144] recognizing the component supported by the component holder;

[0145] using a result of the component recognition and determiningwhether the component is supported properly by the component holder;

[0146] when it is determined that the component is supported by thecomponent holder so that the component will not be mounted properly,discarding the component to a collect station;

[0147] when on the other hand it is determined that the component issupported by the component holder so that the component will be mountedproperly, determining whether a height of the component is greater thanthat of the component mounted on a substrate;

[0148] when it is determined that the height of the component is lessthan that of the mounted component, determining whether the componentholder makes an interference with the mounted component at the mountingof the component supported on the component holder;

[0149] when it is determined that the component holder makes theinterference with the component mounted on the substrate, discarding thecomponent supported by the component holder into the collect sectionwithout mounting the component supported by the component holder;

[0150] when it is determined that the component holder does not make theinterference with the component mounted on the substrate, determiningwhether a height of the component supported by the component holder isgreater than that of the neighboring component mounted on the substrate;and

[0151] when it is determined that the height of the component supportedby the component holder is greater than that of the component mounted onthe substrate, calculating an adjustment for correcting the horizontaland/or angular displacement of the component relative to the componentholder.

[0152] The process has been described in detail in connection withanother embodiment and, therefore, no further discussion will be madethereto.

[0153] The recording medium is preferably used for the system describedin connection with the second embodiment, for example. Also, the programrecorded in the recording medium is installed and then carried out inthe controller 7, 107, or 207.

[0154] Although in the process recorded in the medium the componentsupported by the component holder is discarded if it is determined thatthe component makes the interference with another component mounted onthe substrate, the horizontal and/or angular position of the nozzleand/or the component may be adjusted so as not to interfere with thecomponent mounted on the substrate for the mounting of the componentrather discarding the component as described in connection with thesixth embodiment. Likewise, processes described in connection with otherembodiments can also be memorized in respective recording mediums. Inthis case, each of the recording mediums is used for the installation ofthe program into the controller 7, 107, or 207.

[0155] In conclusion, the present invention prevents the interferencebetween the component holder or the component supported by the componentholder and another component mounted on the substrate even though thereremains a slight clearance between the components, producing a highquality substrate on which components have been mounted.

What is claimed is:
 1. A method for mounting components in which aholder receives a component from a component supply and then places thecomponent on a substrate, comprising the steps of: making a judgementwhether the holder makes an interference with another component mountedon the substrate; if the judgement is affirmative, prohibiting anmounting of the component held by the holder; and if the judgement isnegative, mounting the component held by the holder on the substrate. 2.A method for mounting components, comprising the steps of: causing aholder to receive a component from a component supply; recognizing aposition of the component held by the holder; using the recognizedposition of the component to correct a horizontal and/or angulardisplacement of the component relative to the holder, if necessary; andmounting the component of which position has been corrected, ifnecessary; before mounting, making a judgement whether the holder makesan interference with another component mounted on the substrate; if thejudgement is affirmative, prohibiting an mounting of the component heldby the holder; and if the judgement is negative, mounting the componentheld by the holder on the substrate.
 3. A method in accordance withclaim 1, wherein the judgement further including the steps of: makinganother judgement whether a height of the component held by the holderis greater than that of the component mounted on the substrate; and ifthe another judgement is affirmative, determining that the holder makesno interference with the component mounted on the substrate.
 4. A methodin accordance with claim 2, wherein the judgement further including thesteps of: defining a reference area for the component mounted on thesubstrate; assuming that a displacement of the component relative to theholder is corrected; making a judgement whether at least a part of theholder supporting the component of which displacement has been assumedto be corrected falls outside the reference area, if the judgement isaffirmative, determining that the holder makes the interference with thecomponent mounted on the substrate.
 5. A method for mounting componentsin which a holder receives a component from a component supply and thenplaces the component on a substrate, comprising the steps of: repeatinga plurality of mountings of the components; obtaining a tendency ofinterference of neighboring components on the substrate from theplurality of mountings; and making a correction to reduce the tendencyin the subsequent mountings of the components.
 6. An apparatus formounting components on a substrate, comprising: a component supply forsupplying components to be mounted on the substrate; a holder forreceiving the component from the component supply and then mounting thecomponent on the substrate; and a controller for controlling a movementof the holder; wherein the controller judges before mounting of thecomponent whether the holder interferes with the component mounted onthe substrate and, if affirmative, prohibits the component held by theholder form being mounted on the substrate but, if negative, allows thecomponent held by the holder to be mounted on the substrate.
 7. Anapparatus for mounting components on a substrate, comprising: acomponent supply for supplying components to be mounted on thesubstrate; a holder for receiving the component from the componentsupply and then mounting the component on the substrate; a imageprocessor for recognizing a position of the component held by the holderrelative to the holder; a controller for correcting the position of thecomponent relative to the holder and then causes the holder to place thecomponent on the substrate; wherein the controller makes a judgementbefore mounting of the component whether the holder interferes with thecomponent mounted on the substrate and, if affirmative, prohibits thecomponent held by the holder form being mounted on the substrate but, ifnegative, corrects the position of the component relative to the holderand then allows the component held by the holder to be mounted on thesubstrate.
 8. An apparatus in accordance with claim 7, wherein thecontroller determines in the interference judgement whether a height ofthe component held by the holder is greater than that of the componentmounted on the substrate and, if affirmative, the controller determinesthat the holder does not interfere with the component mounted on thesubstrate.
 9. An apparatus in accordance with claim 7, wherein thecontroller defines a reference area for the component mounted on thesubstrate, assumes that a displacement of the component relative to theholder is corrected, makes a judgement whether at least a part of theholder supporting the component of which displacement has been assumedto be corrected falls outside the reference area, and if affirmative,determines that the holder makes the interference with the componentmounted on the substrate.
 10. An apparatus in accordance with claim 7,wherein the controller defines a reference area for the componentmounted on the substrate, assumes that a displacement of the componentrelative to the holder is corrected, makes a judgement whether at leasta part of the holder supporting the component of which displacement hasbeen assumed to be corrected overlaps the component mounted on thesubstrate, and if affirmative, determines that the holder makes theinterference with the component mounted on the substrate.
 11. Anapparatus in accordance with claim 7, wherein the controller defines areference area for the component mounted on the substrate, the referencearea being expanded from an outline of the component, assumes that adisplacement of the component relative to the holder is corrected, makesa judgement whether at least a part of the holder supporting thecomponent of which displacement has been assumed to be correctedinterferes with the component mounted on the substrate, and ifaffirmative, determines that the holder makes the interference with thecomponent mounted on the substrate.
 12. An apparatus in accordance withclaim 6, wherein if it is determined that the holder interferes with thecomponent mounted on the substrate, the controller corrects a positionof the holder relative to the substrate, makes another judgement whetherthe corrected holder interferes with the component mounted on thesubstrate and, if affirmative, prevents the component from being mountedon the substrate but, if negative, allows the component to be mounted onthe substrate.
 13. An apparatus in accordance with claim 6, furthercomprising another image processor for a recognition of the componentmounted on the substrate; wherein the controller acquires therecognition of the component around which the component held by theholder is to be mounted and then determines whether the holderinterferes with the component mounted on the substrate.
 14. A method formounting components in which a holder receives a component from acomponent supply and then places the component on a substrate,comprising the steps of: using an individual criterion associated to thecomponent held by the holder to determine whether the holder or thecomponent held by the holder interferes with the each component mountedon the substrate.
 15. A method for mounting components in which a holderreceives a component from a component supply and then places thecomponent on a substrate, comprising the steps of: using an individualcriterion associated to a position of the component held by the holderto determine whether the holder or the component held by the holderinterferes with the each component mounted on the substrate.
 16. Amethod in accordance with claim 14, further comprising the steps of:determining, for each of the components to be mounted, a region of thesubstrate on which the component is placed; calculating, for each of thedetermined regions, a distance from another region adjacent the each ofdetermined regions; determining a displacement of the component relativeto the holder holding the component; determining whether thedisplacement is less than the distance determined for the component; andif affirmative, mounting the component on the substrate.
 17. A method inaccordance with claim 14, further comprising the step of: beforemounting the component, determining whether another component supposedto neighbor the component on the substrate has already been mounted onthe substrate; and if negative, the component is permitted to be mountedon the substrate irrespective of its displacement.
 18. A method inaccordance with claim 16, further comprising the step of: furthercomprising the steps of: if the displacement is greater than thedistance, discarding the component held by the holder; and then holdinganother component by the holder for an mounting of the anothercomponent, the another component having the same size with the discardedcomponent.
 19. An apparatus in which a holder receives a component froma component supply and then places the component on a substrate,comprising: a calculator that determines, for each of the components, anarea of the substrate on which the component is mounted and a distancefrom a neighboring component on the substrate; a detector that takes animage of the component held by the holder and determines a displacementof the component relative to the holder; and a controller that, if thedisplacement is less than the distance associated thereto, mounts thecomponent held by the holder on the substrate but, if the displacementis greater than the distance associated thereto, prohibit the componentfrom being mounted on the substrate.
 20. An apparatus in accordance withclaim 19, further comprising: a memory section that includes a list ofcomponents mounted on the substrate, the list being updated after thecomponent has been mounted on the substrate; wherein, if anothercomponent neighboring to the area of the component held by the holderhas not been listed on the list, the controller allows the componentheld by the holder to mount on the substrate irrespective of thedisplacement thereof.
 21. A computer readable recording medium includinga program which is installed in an apparatus for mounting components ona substrate, wherein the apparatus has a component supply for supplyingcomponents, a holder for receiving the component from the componentsupply and then mounting the component on the substrate, and acontroller for controlling an operation for mounting the component onthe substrate, comprising an instruction that determines whether theholder holding the component interferes with another component mountedon the substrate; an instruction that, if it is determined the holderinterferes with another component mounted on the substrate, prevents theholder from mounting the component held by the holder; and aninstruction that, if it is determined the holder does not interfere withanother component mounted on the substrate, allowing the holder to mountthe component held by the holder.